There it is. We've basically already known of T-Mobile's Android plans going down on September 23, but now it's been made official via a press invite for an event at 10:30 AM, where we'll get our first look at the Android-powered HTC Dream (known as the G1 under T-Mo). No word on whether that date will also coincide with phone availability (some have speculated it will come later), but you can bet we'll be there to find out.